A crop conditioner can be provided directly on a crop cutter such as a combine or can be a separate machine that is pulled along behind a cutter or that is simply moved around the field to pick up crop, condition it, and redeposit it on the ground so it can cure. The main function of such a device is to partially crush the crop, thereby breaking stems and making them dry out more quickly. As a rule such devices have at their heart a pair of ribbed rollers that rotate in opposite direction, like a laundry extractor, to pinch the crop and crease the stems where the roller ribs fall.
Various systems described in East German patent 83,484 of H. Schumacher, German patent 2,923,597 of A. Werner, German patent documents 3,331,319 of R. Bellon and 3,711,047 of W. Schulz, French patent 2,568,091 of M. Pruitt (based on US application 06/633,933 use such ribbed rollers. All have the disadvantage that they are only usable on a limited range of crop types. When a thick mat of crop is being conditioned, only the stems lying on the outer surfaces are creased, the inner material being left substantially unconditioned.
It has accordingly been suggested in East German patent 151,551 of T. Eistert to rotate one of the pinch rollers at a speed that is different from that of the other pinch roller. This achieves a slightly better effect, but still leaves the core of the mat being conditioned largely untouched.
In U.S. Pat. No. 4,445,313 of T. ELliot two sets of ribbed pinch rollers are used. The peripheral speeds of both sets of rollers are identical, but their relative angular positions are such that the ribs of the downstream pair fall between the creases created by the upstream pair, thereby crushing the stems at a new location. Once again, conditioning is improved slightly by this system, but not substantially.
Numerous other systems have been proposed in German patent documents 3,923,637, 3,939,618, and 3,939,659, all of K. Schmittbetz as well as in German patent 2,917,191 of G. Krutz (based on U.S. application 06/901,067) and PCT application PCT/EP90/00487 of W. VonAllworden to improve conditioning efficiency. In them the crop is taken in, conditioned, and laid as a mat between 6 mm and 10 mm thick in the field behind the machine. While such machines reduce drying time for the crop considerably, the crop could in theory be conditioned more thoroughly without damage.